1. Field of the Invention
The present invention relates to a servo track writer for use in a hard disc drive, and more particularly, to a servo track writer for use in a hard disc drive, in which the distance between a clock head unit and the hard disc drive can be maintained constant although the hard disc drive moves by a certain distance apart from the clock head unit due to an external force, to thereby detect a clock signal recorded on the hard disc drive with ease.
2. Description of the Related Art
A hard disc drive is one of larg-capacity auxiliary storage devices which are used in a computer. The hard disc drive is comprised of a plurality of circular discs which are spaced by a predetermined distance apart from and stacked over each other, and a plurality of head arms which are rotatably assembled between the discs, to write information on the discs and read information from the discs.
A single disc includes a plurality of concentric tracks on the surface of it. Each concentric track is divided into one or more sectors in which the data is recorded. Servo information such as a track number, a sector number, a head number (disc number), and position control information is recorded on a certain area of each track. The servo information becomes a reference that information is recorded on the disc or information is read therefrom. A device for recording a clock signal and servo information on the hard disc drive in this way is called a servo track writer.
FIG. 3 is a perspective view of a conventional servo track writer for a hard disc drive. As shown, the servo track writer includes a plate-shaped base member 101, a hard disc drive 105 which is fixed on the upper surface of the base member 101 by a plurality of fixing members, a clock head unit 107 spaced by a predetermined distance apart from the hard disc drive 105, and a sliding transfer unit 119 for transferring the clock head unit 107 toward or away from the hard disc drive 105.
A guide rail 109 is protruded and formed on the base member 101 to guide the clock head unit 107 to slide toward the hard disc drive 105. A groove which is engaged with the guide rail 109 is formed on the bottom of a support member 185 supporting the clock head unit 107.
A plurality of discs 113 are spaced apart and stacked over each other in the hard disc drive 105. A head arm 129 for writing information on the discs 113 or reading information from the discs 113 is rotatably installed between the discs 113.
On the upper area of the clock head unit 107 is installed a clock head arm 117 for recording and reading out a clock signal on and from the discs 113 which are rotatably loaded.
Also, the sliding transfer unit 119 includes a driving motor 121 fixedly installed on the base member 101 and spaced apart from the clock head unit 107 by a predetermined distance, a ball screw portion 163 which is rotated by the driving motor 121, and a protruding member 165 extending from the supporting member 164 and threadedly engaged with the ball screw 163.
Meanwhile, a stopper 167 protruding upward from the base member 101 is disposed between the clock head unit 107 and the hard disc drive 105. An adjusting screw 169 which contacts the stopper 167 is provided on the supporting member 164, to limit an access to the hard disc drive 105 when the clock head unit 107 gains access to the hard disc drive 105.
When the hard disc drive 105 is loaded on the base member 101 to write servo information on discs, two horizontal pressing motors 133 operate to press the hard disc drive 105 toward flexing location bars 131. Accordingly, the hard disc drive 105 moves horizontally to the top and the right, and securely contacts the side surfaces of the fixing bars 131. Then, three vertical pressing motors 135 operate to press the hard disc drive 105 vertically to securely contact the upper surface of the base member 101.
When the hard disc drive 105 is fixed on the base member 101 as in the above structure, the driving motor 121 rotates in order to input a clock signal to the track of the discs 113 provided in the hard disc drive 105. As a result, the ball screw 163 is threadedly engaged with the ball threads of the protruding member 165 and rotates, to thereby cause the clock head unit 107 to gain access to the hard disc drive 105. The clock head unit 107 moving toward the hard disc drive 105 does not proceed any more and stops as the adjusting screw 169 connected to the supporting member 164 contacts the stopper 167. When the clock head unit 107 stops, the clock head arm 117 descends toward the discs 113 and the discs 113 of the hard disc drive 105 rotate. As a result, a clock signal is written on a certain area of a track.
When the discs 113 rotate, the clock head arm 117 detects the clock signal recorded on the particular area of the disc track. As the clock signal is detected, the head arm 129 of the hard disc drive 105 writes servo information on the discs 113.
Accordingly, the head arm 129 can write servo information only when a clock signal has been detected. In this way, servo information can be recorded on a certain area of the discs 113.
However, after a clock signal has been recorded on a certain area of the disc track by the clock head arm in the conventional servo track writer, if the hard disc drive is moved by an external force, the clock head arm cannot read the clock signal input to the disc even in the case that servo information tends to be recorded on the disc.
This occurs due to the problem that the distance between the hard disc drive and the clock head unit is varied since the hard disc drive moves independently off the clock head unit. Thus, the whole servo information is recorded on the hard disc drive distortedly, to thereby lower the quality of the hard disc drive.
In addition, since the ball screw in the sliding transfer unit for slidingly transferring the clock head unit is threadedly engaged with the protruding member extended from the support member of the clock head unit, an error in the recording and reading of the clock signal can occur due to a mechanical error such as a backlash.